1. Field of the Invention
This invention relates to vehicle tire pressure management systems and, in particular, to a system and method for adapting control algorithms in vehicle tire pressure management systems.
2. Discussion of Related Art
Conventional tire pressure management systems, also known as central tire inflation systems (CTIS systems), on-board inflation systems and traction systems, are well known in the prior art. Generally, these systems employ a pneumatically controlled wheel valve that is affixed to each vehicle wheel assembly for controlling tire pressure in response to pressure signals from an air control circuit. The air control circuit is connected to each wheel valve via a rotary seal assembly associated with each wheel valve. Tire pressure is monitored by means of a sensor that is positioned in a conduit assembly in the air control circuit. When the wheel valve and certain control valves are opened, the pressure in the conduit equalizes to tire pressure which can then be sensed by the sensor. An electronic control unit reads electrical pressure signals generated by the sensor and appropriately controls the air control circuit in response thereto for inflating or deflating a selected tire.
Although prior art tire pressure management systems have functioned well for their intended purpose, the systems have a significant drawback. The electronic control unit of the system executes a number of control algorithms in the form of software routines that are used to determine a variety of parameters (e.g., tire pressure, line leak rate, and valve position) used by the system. These parameters, however, are significantly affected by the volume in the conduit of the air control circuit-a volume that varies from vehicle to vehicle depending upon such factors as the length of the vehicle and the number of axles and wheels on the vehicle. To enable accurate determinations of the parameters, therefore, conventional tire pressure management systems have required manual calibration of control variables used by the electronic control unit in response to varying air volumes for different vehicles.
The inventors herein have recognized a need for a tire pressure management system and a method for controlling such a system that will minimize and/or eliminate one or more of the above-identified deficiencies.
The present invention provides a tire pressure management system for a vehicle and a method for controlling the system.
A tire pressure management system for a vehicle in accordance with the present invention includes an air source and an air control circuit including a conduit disposed between the air source and a vehicle tire of the vehicle. The system further includes an electronic control unit configured to perform several functions: to determine a volume of the conduit; to adjust a value of a control variable responsive to the volume of the conduit; and to determine a value of a parameter of the tire pressure management system responsive to the value of the control variable. In accordance with some embodiments of the invention, the control variable may comprise a period of time or a pressure in the conduit. Further, in accordance with some embodiments of the invention, the parameter may comprise tire pressure, a leak rate in the conduit, or the position of a valve.
A method for controlling a tire pressure management system of a vehicle in accordance with the present invention includes the step of determining a volume of a conduit disposed between an air source and a vehicle tire of the vehicle. The method further includes the steps of adjusting a value of a control variable responsive to the volume and determining a value of a parameter for the tire pressure management system responsive to the value of the control variable.
A tire pressure management system and method for controlling a tire pressure management system in accordance with the present invention are advantageous. In particular, the inventive system and method enable active or dynamic adaptation of control variables used in tire pressure management systems to determine parameter values responsive to variations in air line volume. As a result, the system can be employed on a wide variety of vehicles without requiring expensive and time consuming manual calibration of the control algorithms.
These and other advantages of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example.